diff --git a/spec/panel-container-element-spec.coffee b/spec/panel-container-element-spec.coffee
index f7d2c1dd9..d3574327c 100644
--- a/spec/panel-container-element-spec.coffee
+++ b/spec/panel-container-element-spec.coffee
@@ -51,6 +51,7 @@ describe "PanelContainerElement", ->
         container.addPanel(panel1)
         expect(element.childNodes.length).toBe 1
         expect(element.childNodes[0]).toHaveClass 'left'
+        expect(element.childNodes[0]).toHaveClass 'tool-panel' # legacy selector support
         expect(element.childNodes[0]).toHaveClass 'panel-left' # legacy selector support
 
         expect(element.childNodes[0].tagName).toBe 'ATOM-PANEL'
@@ -81,6 +82,7 @@ describe "PanelContainerElement", ->
         container.addPanel(panel1)
         expect(element.childNodes.length).toBe 1
         expect(element.childNodes[0]).toHaveClass 'bottom'
+        expect(element.childNodes[0]).toHaveClass 'tool-panel' # legacy selector support
         expect(element.childNodes[0]).toHaveClass 'panel-bottom' # legacy selector support
         expect(element.childNodes[0].tagName).toBe 'ATOM-PANEL'
         expect(panel1.getView()).toHaveClass 'one'
@@ -124,5 +126,8 @@ describe "PanelContainerElement", ->
       container.addPanel(panel1)
 
       expect(panel1.getView()).toHaveClass 'modal'
-      expect(panel1.getView()).toHaveClass 'overlay' # legacy selector support
-      expect(panel1.getView()).toHaveClass 'from-top' # legacy selector support
+
+      # legacy selector support
+      expect(panel1.getView()).not.toHaveClass 'tool-panel'
+      expect(panel1.getView()).toHaveClass 'overlay'
+      expect(panel1.getView()).toHaveClass 'from-top'
diff --git a/src/panel-container-element.coffee b/src/panel-container-element.coffee
index 22558b362..880fd3267 100644
--- a/src/panel-container-element.coffee
+++ b/src/panel-container-element.coffee
@@ -18,7 +18,7 @@ class PanelContainerElement extends HTMLElement
     if @model.isModal()
       panelElement.classList.add("overlay", "from-top")
     else
-      panelElement.classList.add("panel-#{@model.getLocation()}")
+      panelElement.classList.add("tool-panel", "panel-#{@model.getLocation()}")
 
     if index >= @childNodes.length
       @appendChild(panelElement)
diff --git a/src/panel-element.coffee b/src/panel-element.coffee
index 72c04b140..eec1d91b5 100644
--- a/src/panel-element.coffee
+++ b/src/panel-element.coffee
@@ -12,7 +12,6 @@ class PanelElement extends HTMLElement
     @appendChild(view)
     callAttachHooks(view) # for backward compatibility with SpacePen views
 
-    @classList.add("tool-panel")
     @classList.add(@model.getClassName().split(' ')...) if @model.getClassName()?
     @subscriptions.add @model.onDidChangeVisible(@visibleChanged.bind(this))
     @subscriptions.add @model.onDidDestroy(@destroyed.bind(this))